Numerical Investigation of the Impact of the Rectangular Nozzle Aspect Ratio on Liquid Jet in Crossflow

High-fidelity simulation is conducted to investigate liquid jet in crossflow, specifically regarding the rectangular nozzle. The influence of aspect ratio (AR) of nozzles on the atomization characteristics of liquid column in the process of primary breakup is explored by the analysis of the flow structure of crossflow and liquid column. The aspect ratio is ranging from 1 to 8. The results indicate that as the increase of aspect ratio, the disturbance of crossflow to the liquid on the sides is weakened. While the thickness of liquid column also gradually decreases, which enables smaller disturbances to promote droplet shedding. Therefore, surface breakup first weakens and then strengthens. In the column breakup process, the increase of aspect ratio causes crossflow to become the main factor affecting column breakup, and the influence of air pressure gradually weakens. This indicates a shift in the mechanism of surface instability from "Rayleigh-Taylor" (R-T) instability to "Kelvin-Helmholtz" (K-H) instability.